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Abstract:

An apparatus for inspecting a nuclear reactor may include a track, arm,
fixing device, and effector. The arm may be operatively connected to the
track, the fixing device may be operatively connected to the track, and
the effector may be operatively connected to the arm. The arm may have
contracted and expanded lengths. The expanded length may be greater than
two times the contracted length. The track may include one or more motors
adapted to move the arm relative to the track. A method of inspecting,
performing maintenance on, or repairing a reactor may include:
operatively connecting a fixing device, track, arm, and effector to form
an apparatus; inserting the apparatus into the reactor; fixing the
apparatus within the reactor; and operating the apparatus. A method of
operating a reactor may include shutting down; inspecting, performing
maintenance on, or repairing the reactor; and starting up the reactor.

Claims:

1. A method of inspecting, performing maintenance on, or repairing a
nuclear reactor, the method comprising:operatively connecting a fixing
device, a first track, an arm, and an effector to form an
apparatus;inserting the apparatus into the reactor;fixing the apparatus
within the reactor; andoperating the apparatus;wherein the arm has a
contracted length,wherein the arm has an expanded length, andwherein the
expanded length is greater than two times the contracted length.

2. A method of operating a nuclear reactor, the method comprising:shutting
down the reactor;inspecting, performing maintenance on, or repairing the
reactor; andstarting up the reactor;wherein the reactor is inspected,
maintenance is performed on the reactor, or the reactor is repaired
according to the method of claim 1.

3. An apparatus for inspecting a nuclear reactor, the apparatus
comprising:a first track;an arm;a fixing device; andan effector;wherein
the arm is operatively connected to the first track,wherein the fixing
device is operatively connected to the first track,wherein the effector
is operatively connected to the arm,wherein the arm has a contracted
length,wherein the arm has an expanded length, andwherein the expanded
length is greater than two times the contracted length.

4. The apparatus of claim 3, wherein the first track comprises one or more
motors adapted to move the arm relative to the first track.

5. The apparatus of claim 3, wherein the first track comprises one or more
motors adapted to move the arm along the first track.

6. The apparatus of claim 3, wherein the first track comprises one or more
motors adapted to move the arm relative to the operative connection of
the arm to the first track.

7. The apparatus of claim 3, wherein the first track comprises one or more
motors adapted to rotate the arm relative to the first track.

8. The apparatus of claim 3, wherein the first track comprises first,
second, and third motors,wherein the first motor is adapted to move the
arm relative to the operative connection of the arm to the first
track,wherein the second motor is adapted to move the arm along the first
track, andwherein the third motor is adapted to rotate the arm relative
to the first track.

9. The apparatus of claim 3, further comprising:a cable management-system.

10. The apparatus of claim 9, wherein the first track comprises at least a
portion of the cable management system.

11. The apparatus of claim 9, wherein the arm comprises at least a portion
of the cable management system.

12. The apparatus of claim 3, wherein the arm is adapted to move relative
to the first track.

13. The apparatus of claim 3, wherein the arm is adapted to move along the
first track.

14. The apparatus of claim 3, wherein the arm is adapted to move relative
to the operative connection of the arm to the first track.

15. The apparatus of claim 3, wherein the arm is adapted to rotate
relative to the first track.

16. The apparatus of claim 3, wherein the arm comprises one or more second
tracks.

17. The apparatus of claim 16, wherein at least one of the one or more
second tracks is a curved track.

18. The apparatus of claim 16, wherein at least one of the one or more
second tracks is a substantially straight track.

19. The apparatus of claim 16, wherein at least one of the one or more
second tracks includes at least three sections.

20. The apparatus of claim 19, wherein the at least three sections are
adapted to contract the arm to the contracted length,wherein the at least
three sections are adapted to expand the arm to the expanded length,
orwherein the at least three sections are adapted to contract the arm to
the contracted length and the at least three sections are adapted to
expand the arm to the expanded length.

21. The apparatus of claim 3, wherein the fixing device comprises one or
more scissor jacks.

22. The apparatus of claim 3, wherein the fixing device comprises one or
more hydraulic cylinders, one or more pneumatic cylinders, or one or more
hydraulic cylinders and one or more pneumatic cylinders.

23. The apparatus of claim 3, wherein the fixing device comprises one or
more hydraulic pistons, one or more pneumatic pistons, or one or more
hydraulic pistons and one or more pneumatic pistons.

24. The apparatus of claim 3, wherein the operative connection of the
effector to the arm comprises a bracket.

25. The apparatus of claim 24, wherein the bracket is spring-loaded.

26. The apparatus of claim 3, wherein the operative connection of the
effector to the arm comprises a gimbal.

27. The apparatus of claim 3, wherein the effector comprises one or more
sensors.

28. The apparatus of claim 27, wherein the one or more sensors comprise at
least one camera.

29. The apparatus of claim 27, wherein the one or more sensors comprise at
least one video camera.

30. The apparatus of claim 27, wherein the one or more sensors comprise at
least one transducer.

31. The apparatus of claim 27, wherein the one or more sensors comprise at
least one ultrasonic transducer.

32. An apparatus for inspecting a nuclear reactor, the apparatus
comprising:a first track;an arm;a fixing device; andan effector;wherein
the arm is operatively connected to the first track,wherein the fixing
device is operatively connected to the first track,wherein the effector
is operatively connected to the arm, andwherein the first track includes
one or more motors adapted to move the arm relative to the first track.

33. The apparatus of claim 32, wherein the first track comprises one or
more motors adapted to move the arm along the first track.

34. The apparatus of claim 32, wherein the first track comprises one or
more motors adapted to move the arm relative to the operative connection
of the arm to the first track.

35. The apparatus of claim 32, wherein the first track comprises one or
more motors adapted to rotate the arm relative to the first track.

36. The apparatus of claim 32, wherein the first track comprises first,
second, and third motors,wherein the first motor is adapted to move the
arm relative to the operative connection of the arm to the first
track,wherein the second motor is adapted to move the arm along the first
track, andwherein the third motor is adapted to rotate the arm relative
to the first track.

37. An apparatus for performing maintenance on or repairing a nuclear
reactor, the apparatus comprising:a first track;an arm;a fixing
device;one or more sensors; andone or more tools;wherein the arm is
operatively connected to the first track,wherein the fixing device is
operatively connected to the first track,wherein the one or more sensors,
the one or more tools, or the one or more sensors and the one or more
tools are operatively connected to the arm,wherein the arm has a
contracted length,wherein the arm has an expanded length, andwherein the
expanded length is greater than two times the contracted length.

38. An apparatus for performing maintenance on or repairing a nuclear
reactor, the apparatus comprising:a first track;an arm;a fixing
device;one or more sensors; andone or more tools;wherein the arm is
operatively connected to the first track,wherein the fixing device is
operatively connected to the first track,wherein the one or more sensors,
the one or more tools, or the one or more sensors and the one or more
tools are operatively connected to the arm, andwherein the first track
includes one or more motors adapted to move the arm relative to the first
track.

Description:

BACKGROUND

[0001]1. Field

[0002]Example embodiments relate to inspection, maintenance, and repair
apparatuses and methods for nuclear reactors. Additionally, example
embodiments relate to inspection, maintenance, and repair apparatuses and
methods for nuclear reactors in confined areas, such as within the
downcomer annulus between the reactor pressure vessel and the core
shroud.

[0005]Core shroud 110 is a stainless steel cylinder that surrounds core
102. Core 102 includes a multiplicity of fuel bundle assemblies 112 (two
2×2 arrays, for example, are shown in FIG. 1). Each array of fuel
bundle assemblies 112 is supported at its top by top guide 114 and at its
bottom by core plate 116. Top guide 114 provides lateral support for the
top of fuel bundle assemblies 112 and maintains correct fuel-channel
spacing to permit control rod insertion.

[0007]The steam-water mixture flows through standpipes 124 and enters
steam separators 126 (which may be, for example, of the axial-flow,
centrifugal type). Steam separators 126 substantially separate the
steam-water mixture into liquid water and steam. The separated liquid
water mixes with feedwater in mixing plenum 128. This mixture then
returns to core 102 via downcomer annulus 108. The separated steam passes
through steam dryers 130 and enters steam dome 132. The dried steam is
withdrawn from RPV 100 via steam outlet 134 for use in turbines and other
equipment (not shown).

[0008]The BWR also includes a coolant recirculation system that provides
the forced convection flow through core 102 necessary to attain the
required power density. A portion of the water is sucked from the lower
end of downcomer annulus 108 via recirculation water outlet 136 and
forced by a centrifugal recirculation pump (not shown) into a plurality
of jet pump assemblies 138 (only one of which is shown) via recirculation
water inlets 140. The jet pump assemblies 138 are circumferentially
distributed around the core shroud 110 and provide the required reactor
core flow. A typical BWR includes 16 to 24 inlet mixers.

[0009]As shown in FIG. 1, related art jet pump assemblies 138 typically
include a pair of inlet mixers 142. Each inlet mixer 142 has an elbow 144
welded thereto which receives pressurized driving water from a
recirculation pump (not shown) via inlet riser 146. An exemplary inlet
mixer 142 includes a set of five nozzles circumferentially distributed at
equal angles about the inlet mixer axis. Each nozzle is tapered radially
inwardly at its outlet. The jet pump is energized by these convergent
nozzles. Five secondary inlet openings are radially outside of the nozzle
exits. Therefore, as jets of water exit the nozzles, water from downcomer
annulus 108 is drawn into inlet mixer 142 via the secondary inlet
openings, where it is mixed with coolant water from the recirculation
pump. The coolant water then flows into diffuser 148.

[0010]Core shroud 110 may include, for example, a shroud head flange (not
shown) for supporting shroud head 122, an upper shroud wall (not shown)
having a top end welded to the shroud head flange, a top guide support
ring (not shown) welded to the bottom end of the upper shroud wall, a
middle shroud wall (not shown) having a top end welded to the top guide
support ring and including two or three vertically stacked shell sections
(not shown) joined by mid-shroud attachment weld(s), and an annular core
plate support ring (not shown) welded to the bottom end of the middle
shroud wall and to the top end of a lower shroud wall (not shown). The
entire shroud is supported by a shroud support (not shown), which is
welded to the bottom of the lower shroud wall, and by an annular jet pump
support plate (not shown), which is welded at its inner diameter to the
shroud support and at its outer diameter to RPV 100.

[0011]Typically, the material of core shroud 110 and associated welds is
austenitic stainless steel having reduced carbon content. The
heat-affected zones of the shroud girth welds, including the mid-shroud
attachment weld(s), have residual weld stresses. Therefore, mechanisms
are present for mid-shroud attachment weld(s) and other girth welds to be
susceptible to intergranular stress corrosion cracking (IGSCC).

[0012]IGSCC in the heat affected zone of any shroud girth seam weld
diminishes the structural integrity of core shroud 110, which vertically
and horizontally supports top guide 114 and shroud head 122. In
particular, a cracked core shroud 110 increases the risks posed by a
loss-of-coolant accident (LOCA) or seismic loads. During a LOCA, the loss
of coolant from RPV 100 produces a loss of pressure above shroud head 122
and an increase in pressure inside core shroud 110, i.e., underneath
shroud head 122. The result is an increased lifting force on shroud head
122 and on the upper portions of core shroud 110 to which shroud head 122
is bolted. If core shroud 110 has fully cracked girth welds, the lifting
forces produced during a LOCA could cause core shroud 110 to separate
along the areas of cracking, producing undesirable leaking of reactor
coolant. Also, if the weld zones of core shroud 110 fail due to IGSCC,
there is a risk of misalignment from seismic loads and damage to core 102
and the control rod components, which would adversely affect control rod
insertion and safe shutdown.

[0013]Thus, core shroud 110 needs to be examined periodically to determine
its structural integrity and the need for repair. Ultrasonic inspection
is a known technique for detecting cracks in nuclear reactor components.
The inspection area of primary interest is the outside surface of core
shroud 110 at the horizontal and/or vertical mid-shroud attachment
weld(s). However, core shroud 110 is difficult to access. Installation
access is limited to the annular space between the outside of core shroud
110 and the inside of RPV 100, between adjacent jet pump assemblies 138.
Scanning operation access is additionally restricted within the narrow
space between core shroud 110 and jet pump assemblies 138, which is about
0.5 inch wide in some locations. The inspection areas are highly
radioactive and may be located under water, 50 feet or more below an
operator's work platform. As a result, inspection of core shroud 110
and/or RPV 100, as well as all other inspection, maintenance, and repair
within downcomer annulus 108 often is difficult and complicated.

[0014]Solutions to the problem of inspecting core shroud 110 have been
proposed, as discussed, for example, in U.S. Pat. No. 5,586,155 ("the
'155 patent"). The disclosure of the '155 patent is incorporated in this
application by reference. However, these proposed solutions do not
include inspection, maintenance, and repair apparatuses and methods for
nuclear reactors similar to the present invention.

SUMMARY

[0015]Example embodiments relate to inspection, maintenance, and repair
apparatuses and methods for nuclear reactors. Additionally, example
embodiments relate to inspection, maintenance, and repair apparatuses and
methods for nuclear reactors in confined areas, such as within the
downcomer annulus between the reactor pressure vessel and the core
shroud.

[0016]In an example embodiment, a method of inspecting a nuclear reactor
may include: operatively connecting a fixing device, a first track, an
arm, and an effector to form an inspection apparatus; inserting the
inspection apparatus into the reactor; fixing the inspection apparatus
within the reactor; and/or operating the inspection apparatus. The arm
may have a contracted length. The arm may have an expanded length. The
expanded length may be greater than two times the contracted length.

[0017]In another example embodiment, a method of performing maintenance on
a nuclear reactor may include: operatively connecting a fixing device, a
first track, an arm, and one or more tools to form a maintenance
apparatus; inserting the maintenance apparatus into the reactor; fixing
the maintenance apparatus within the reactor; and/or operating the
maintenance apparatus. The arm may have a contracted length. The arm may
have an expanded length. The expanded length may be greater than two
times the contracted length.

[0018]In yet another example embodiment, a method of repairing a nuclear
reactor may include: operatively connecting a fixing device, a first
track, an arm, and one or more sensors, one or more tools, or one or more
sensors and one or more tools to form a repair apparatus; inserting the
repair apparatus into the reactor; fixing the repair apparatus within the
reactor; and/or operating the repair apparatus. The arm may have a
contracted length. The arm may have an expanded length. The expanded
length may be greater than two times the contracted length.

[0019]In still another example embodiment, an apparatus for inspecting a
nuclear reactor may include: a first track; an arm; a fixing device;
and/or an effector. The arm may be operatively connected to the first
track. The fixing device may be operatively connected to the first track.
The effector may be operatively connected to the arm. The arm may have a
contracted length. The arm may have an expanded length. The expanded
length may be greater than two times the contracted length.

[0020]In a further example embodiment, an apparatus for inspecting a
nuclear reactor may include: a first track; an arm; a fixing device;
and/or an effector. The arm may be operatively connected to the first
track. The fixing device may be operatively connected to the first track.
The effector may be operatively connected to the arm. The first track may
include one or more motors adapted to move the arm relative to the first
track.

[0021]In another further example embodiment, an apparatus for performing
maintenance on a nuclear reactor may include: a first track; an arm; a
fixing device; and/or one or more tools. The arm may be operatively
connected to the first track. The fixing device may be operatively
connected to the first track. The one or more tools may be operatively
connected to the arm. The arm may have a contracted length. The arm may
have an expanded length. The expanded length may be greater than two
times the contracted length.

[0022]In yet another further example embodiment, an apparatus for
performing maintenance on a nuclear reactor, the apparatus comprising: a
first track; an arm; a fixing device; and/or one or more tools. The arm
may be operatively connected to the first track. The fixing device may be
operatively connected to the first track. The one or more tools may be
operatively connected to the arm. The first track may include one or more
motors adapted to move the arm relative to the first track.

[0023]In still another further example embodiment, an apparatus for
repairing a nuclear reactor may include: a first track; an arm; a fixing
device; one or more sensors; and/or one or more tools. The arm may be
operatively connected to the first track. The fixing device may be
operatively connected to the first track. The one or more sensors, the
one or more tools, or the one or more sensors and the one or more tools
may be operatively connected to the arm. The arm may have a contracted
length. The arm may have an expanded length. The expanded length may be
greater than two times the contracted length.

[0024]In an additional example embodiment, an apparatus for repairing a
nuclear reactor may include: a first track; an arm; a fixing device; one
or more sensors; and/or one or more tools. The arm may be operatively
connected to the first track. The fixing device may be operatively
connected to the first track. The one or more sensors, the one or more
tools, or the one or more sensors and the one or more tools may be
operatively connected to the arm. The first track may include one or more
motors adapted to move the arm relative to the first track.

[0025]In another additional example embodiment, a kit for inspecting,
performing maintenance on, or repairing a nuclear reactor may include: a
first track; an arm; and/or a fixing device. The arm may be adapted to be
operatively connected to the first track. The fixing device may be
adapted to be operatively connected to the first track. The arm may have
a contracted length. The arm may have an expanded length. The expanded
length may be greater than two times the contracted length.

[0026]In yet another additional example embodiment, a kit for inspecting,
performing maintenance on, or repairing a nuclear reactor may include: a
first track; an arm; and/or a fixing device. The arm may be adapted to be
operatively connected to the first track. The fixing device may be
adapted to be operatively connected to the first track. The first track
may include one or more motors adapted to move the arm relative to the
first track.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]The above and/or other aspects and advantages will become more
apparent and more readily appreciated from the following detailed
description of example embodiments taken in conjunction with the
accompanying drawings, in which:

[0028]FIG. 1 is a sectional view, with parts cut away, of a typical RPV in
a related art BWR;

[0029]FIG. 2 is a perspective view of an inspection, maintenance, and
repair apparatus for nuclear reactors, according to an example
embodiment;

[0030]FIG. 3 is an exploded, perspective view of an arm of the apparatus
of FIG. 2;

[0031]FIG. 4 is a reverse exploded, perspective view of the arm of FIG. 3;

[0032]FIG. 5 is a front perspective view of a second track of the arm of
FIG. 3;

[0033]FIG. 6 is a top view of the second track of FIG. 5;

[0034]FIG. 7 is a rear view of the second track of FIG. 6;

[0035]FIG. 8 is a first detailed view of the second track of FIG. 7;

[0036]FIG. 9 is a second detailed view of the second track of FIG. 7;

[0037]FIG. 10 is a third detailed view of the second track of FIG. 7;

[0038]FIG. 11 is an exploded, perspective view of a first track of the
apparatus of FIG. 2;

[0039]FIG. 12 is a reverse exploded, perspective view of the first track
of FIG. 11;

[0040]FIG. 13 is a reverse exploded, perspective view of a first portion
of the first track of FIG. 11;

[0041]FIG. 14 is a reverse exploded, perspective view of a second portion
of the first track of FIG. 11;

[0042]FIG. 15 is a perspective view of a fixing device of the apparatus of
FIG. 2; and

[0043]FIG. 16 is a reverse perspective view of the fixing device of FIG.
15.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0044]Example embodiments will now be described more fully with reference
to the accompanying drawings. Embodiments, however, may be embodied in
many different forms and should not be construed as being limited to the
example embodiments set forth herein. Rather, these example embodiments
are provided so that this disclosure will be thorough and complete, and
will fully convey the scope to those skilled in the art.

[0045]It will be understood that when a component is referred to as being
"on," "connected to," "coupled to," or "fixed to" another component, it
may be directly on, connected to, coupled to, or fixed to the other
component or intervening components may be present. In contrast, when a
component is referred to as being "directly on," "directly connected to,"
"directly coupled to," or "directly fixed to" another component, there
are no intervening components present. As used herein, the term "and/or"
includes any and all combinations of one or more of the associated listed
items.

[0046]It will be understood that although the terms first, second, third,
etc., may be used herein to describe various elements, components,
regions, layers, and/or sections, these elements, components, regions,
layers, and/or sections should not be limited by these terms. These terms
are only used to distinguish one element, component, region, layer, or
section from another element, component, region, layer, or section. Thus,
a first element, component, region, layer, or section discussed below
could be termed a second element, component, region, layer, or section
without departing from the teachings of the example embodiments.

[0047]Spatially relative terms, such as "beneath," "below," "lower,"
"above," "upper," and the like may be used herein for ease of description
to describe one component and/or feature relative to another component
and/or feature, or other component(s) and/or feature(s), as illustrated
in the drawings. It will be understood that the spatially relative terms
are intended to encompass different orientations of the device in use or
operation in addition to the orientation depicted in the figures.

[0048]The terminology used herein is for the purpose of describing
particular example embodiments only ,and is not intended to be limiting.
As used herein, the singular forms "a," "an," and "the" are intended to
include the plural forms as well, unless the context clearly indicates
otherwise. It will be further understood that the terms "comprises,"
"comprising," "includes," and/or "including," when used in this
specification, specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations,
elements, and/or components.

[0049]Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which example
embodiments belong. It will be further understood that terms, such as
those defined in commonly used dictionaries, should be interpreted as
having a meaning that is consistent with their meaning in the context of
the relevant art and should not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.

[0050]Reference will now be made to example embodiments, which are
illustrated in the accompanying drawings, wherein like reference numerals
refer to the like components throughout.

[0051]FIG. 2 is a perspective view of an inspection, maintenance, and
repair apparatus for nuclear reactors, according to an example
embodiment. As shown in FIG. 2, apparatus 200 for inspection,
maintenance, and/or repair of nuclear reactors may include: arm 202,
first track 204, fixing device 206, and/or effector 208. Arm 202 may be
operatively connected to first track 204. Fixing device 206 may be
operatively connected to first track 204. Effector 208 may be operatively
connected to arm 202.

[0052]Apparatus 200 may allow a reduced number of movements for full or
limited coverage of inspection, maintenance, and/or repair. At least
partially as a result, apparatus 200 may shorten inspection cycles and/or
simplify inspection plans.

[0053]Arm 202 may have a contracted length and an expanded length. The
expanded length may be greater than two times the contracted length. For
example, the expanded length may be about 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6,
6.5, 7, 7.5, 8, or more times the contracted length. In addition or in
the alternative, first track 204 may include one or more motors adapted
to move arm 202 relative to first track 204.

[0054]Arm 202 may be adapted to move relative to first track 204. For
example, arm 202 may be adapted to move along first track 204, to move
relative to operative connection 210 of arm 202 to first track 204,
and/or to rotate relative to first track 204.

[0055]Effector 208 may include one or more sensors. For example, the one
or more sensors may include at least one camera, at least one video
camera, at least one transducer, at least one ultrasonic transducer,
and/or at least one scanner. At least one of the one or more sensors may
be, for example, sensitive to touch and/or pressure, moisture,
temperature, pH, conductivity, and/or the presence and/or concentration
of chemicals.

[0056]In addition or in the alternative, effector 208 may include one or
more tools, such as tools for cleaning the reactor, finding and/or
retrieving reactor components, welding, and/or electrical discharge
machining ("EDM").

[0057]In an example embodiment, apparatus 200 may be inserted into the
reactor on the end of a long pole (not shown) connected to adapter
assembly 212. The pole may be about 60 feet to about 80 feet in length,
at least in part due to one or more of the distance from a workers'
platform above the reactor to the reactor itself, the radiation exposure
in the area of the workers' platform and the reactor, and the fact that
the reactor may be substantially full of water when apparatus 200 is
inserted into the reactor. One or more workers may control the pole to
position the apparatus 200 as required in the reactor. That position
might be, for example, between the outside of core shroud 110 and the
inside of RPV 100, with first track 204, effector 208, and/or one or more
of adjustable feet 214 substantially in contact with core shroud 110
and/or fixing device 206 substantially in contact with RPV 100. Apparatus
200 also may be inserted into the reactor using a remotely operated
vehicle ("ROV") (not shown), a cable/chain hoist (not shown), or similar
device(s).

[0058]When inserting apparatus 200 into the reactor, arm 202 may be
rotated to be substantially parallel to first track 204. This parallelism
may assist the one or more workers in expeditiously positioning apparatus
200 in the reactor.

[0059]In an example embodiment, once apparatus 200 is properly positioned,
the one or more workers may cause fixing device 206 to exert pressure on
RPV 100 to force first track 204, effector 208, and/or one or more of
adjustable feet 214 to contact core shroud 110, fixing apparatus 200 in
position. Apparatus 200 also may be fixed in position by fixing device
206 in the form of a mast, scan arm, or equivalent that may be, for
example, connected to core shroud 110 and/or the shroud head flange (not
shown), or may ride on the steam dam (not shown) of the reactor.

[0060]With apparatus 200 fixed in position, effector 208 may be positioned
as required using arm 202 and first track 204. For example, assuming that
first track 204 is fixed in a vertical orientation, arm 202 may be moved
along first track 204 to raise or lower operative connection 210 (and,
thus, to raise or lower effector 208), arm 202 may be moved relative to
operative connection 210 (and, thus, to change the distance of effector
208 from operative connection 210), and/or arm 202 may be rotated
relative to first track 204 to change the angle of arm 202 relative to
first track 204 (and, thus, to change the angular position of effector
208). The narrow profile of arm 202 and effector 208 may allow effector
208 access to confined spaces inaccessible by other devices, such as
ROVs.

[0061]Effector 208 may be positioned by any of these "degrees of freedom"
independently or by two or more simultaneously. Additionally or in the
alternative, effector 208 may have "degrees of freedom" other than those
discussed above. Some examples are in included in the discussion of arm
202 below.

[0062]Apparatus 200 may further include a cable management system. The
cable management system helps to manage one or more umbilical cables (not
shown) that, for example, may supply power (i.e., electrical, pneumatic,
and/or hydraulic (water-based)) to apparatus 200, may provide control
signals to apparatus 200, and/or may provide the one or more workers with
sensors signals from apparatus 200. The one or more umbilical cables may
reach from a workers' platform to apparatus 200 and/or effector 208.

[0063]First track 204 may include at least a portion of the cable
management system. Similarly, arm 202 may include at least a portion of
the cable management system. In an example embodiment, first track 204
may include a first portion of the cable management system and arm 202
may include a second portion of the cable management system.

[0065]Second track 300 may include three or more sections. Typically,
because the sections are stacked, more sections results in a thicker
second track 300.

[0066]Sections of second track 300 may be manufactured with a standardized
radius of curvature or standardized radii of curvature. However, the
radius of curvature of second track 300 does not need to exactly match
that of core shroud 110, RPV 100, etc. This may be true, for example, if
effector 208 does not have to be in direct contact with core shroud 110,
RPV 100, etc. In addition or in the alternative, this may be true because
effector 208 may be operatively connected to arm 202 using effector
bracket 322, and effector bracket 322 may be spring-loaded or equivalent
to influence effector 208 toward core shroud 110, RPV 100, etc.

[0067]In an example embodiment, crossbar 302 may function primarily as a
structural support.

[0068]In addition to the degrees of freedom discussed above, effector 208
may have additional degrees of freedom. For example, effector 208 may be
operatively connected to arm 202 using a gimbal or some other device. In
an example embodiment, effector 208 may be operatively connected to arm
202 anywhere on arm 202.

[0069]As discussed above, arm 202 may include at least a portion of the
cable management system. That portion may include, for example, one or
more of guide block 304; guides 306 and/or 308; roller brackets 310, 312,
and/or 314; and rollers 316, 318, and/or 320.

[0070]FIG. 5 is a front perspective view of second track 300 of arm 202 of
FIG. 3, FIG. 6 is a top view of second track 300 of FIG. 5, and FIG. 7 is
a rear view of second track 300 of FIG. 6. FIG. 8 is a first detailed
view of second track 300 of FIG. 7, FIG. 9 is a second detailed view of
second track 300 of FIG. 7, and FIG. 10 is a third detailed view of
second track 300 of FIG. 7. As shown in FIGS. 5-9, second track 300 may
include first section 500, second section 502, third section 504, and/or
fourth section 506. Fourth section 506 may be fixed to first track 204.

[0072]In FIG. 9, upper rail 904 and lower rail 906 of first section 500
are depicted as v-shaped rails. Although other shapes are possible, one
or more inner rollers 912 of second section 502 ride on one or both of
upper rail 904 and lower rail 906. Similarly, inner upper rail 922 and
inner lower rail 924 of third section 504 are depicted as v-shaped rails.
Although other shapes are possible, one or more outer rollers 914 of
second section 502 ride on one or both of inner upper rail 922 and inner
lower rail 924. In the same way, outer upper rail 926 and outer lower
rail 928 of third section 504 are depicted as v-shaped rails. Although
other shapes are possible, one or more rollers (not shown) of fourth
section 506 ride on one or both of outer upper rail 926 and outer lower
rail 928.

[0073]Upper gear rack 902 and inner upper gear rack 918 may be connected
by a first idler gear (not shown) so that when second track 300 is
expanded or contracted by the driving of outer upper gear rack 920, first
section 500 is driven by third section 504. Similarly, lower gear rack
910 and lower gear rack 932 may be connected by a second idler gear (not
shown) so that when second track 300 is expanded or contracted by the
driving of outer upper gear rack 920, second section 502 is driven by
fourth section 506. In this way, when second track 300 is expanded or
contracted by the driving of outer upper gear rack 920, first section
500, second section 502, and third section 504 may all move
simultaneously relative to fourth section 506. In a first example
embodiment, the extent of this simultaneous movement is proportional
between sections. In a second example embodiment, the extent of the
simultaneous movement is identical between sections.

[0075]In another example embodiment, apparatus 200 for inspection,
maintenance, and/or repair of nuclear reactors may include: arm 202,
first track 204, fixing device 206, and/or effector 208. Arm 202 may
include a second track with a curvature opposite to that of second track
300. In this case, the apparatus 200 may be positioned, for example,
between the outside of core shroud 110 and the inside of RPV 100, with
first track 204, effector 208, and/or one or more of adjustable feet 214
substantially in contact with RPV 100 and/or fixing device 206
substantially in contact with core shroud 110. The apparatus 200 may be
used, for example, to inspect the inner surface of RPV 100.

[0076]In a further example embodiment, apparatus 200 for inspection,
maintenance, and/or repair of nuclear reactors may include: arm 202,
first track 204, fixing device 206, and/or effector 208. Arm 202 may
include a second track that is substantially straight. In this case, the
apparatus 200 may be used, for example, to inspect any substantially flat
surface in the reactor.

[0077]In yet another example embodiment, apparatus 200 for inspection,
maintenance, and/or repair of nuclear reactors may include: arm 202,
first track 204, fixing device 206, and/or effector 208. Arm 202 may
include one or more second tracks. At least one of the one or more second
tracks may be a curved track. In addition or in the alternative, at least
one of the one or more second tracks may be a substantially straight
track. In addition or in the alternative, at least one of the one or more
second tracks may include at least three sections. In an example
embodiment, the at least three sections may be are adapted to contract
arm 202 to the contracted length and/or to expand arm 202 to the expanded
length.

[0078]FIG. 11 is an exploded, perspective view of first track 204 of
apparatus 200 of FIG. 2, while FIG. 12 is a reverse exploded, perspective
view of first track 204 of FIG. 11, FIG. 13 is a reverse exploded,
perspective view of a first portion of first track 204 of FIG. 11, and
FIG. 14 is a reverse exploded, perspective view of a second portion of
first track 204 of FIG. 11.

[0079]As shown in FIGS. 11-14, first track 204 may include first motor
1200, second motor 1202, and/or third motor 1204. First track 204 also
may include first shaft 1206, second shaft 1208, and/or third shaft 1210.
Additionally, first track 204 may include first rail 1212 and/or second
rail 1214.

[0081]Additionally, first track 204 may include extra components known to
one of skill in the art (as shown in FIGS. 11-14), such as, for example,
one or more ball bearings, brackets, cable guides, caps, drive gears,
gaskets, idler gears, lock nuts, miter gears, pinions, screws, seals,
shaft extensions, spacers, washers, and worm gears. In an example
embodiment, first track 204 includes three gears--a pinion gear, an idler
gear, and a worm gear--for each of first motor 1200, second motor 1202,
and third motor 1204 (the motor turns the pinion gear, the pinion gear
turns the idler gear, and the idler gear turns the worm gear).

[0082]In a first example embodiment, first track 204 may include one or
more motors (i.e., first motor 1200, second motor 1202, and/or third
motor 1204) adapted to move arm 202 relative to first track 204. In a
second example embodiment, first track 204 may include one or more motors
adapted to move arm 202 along first track 204. In a third example
embodiment, first track 204 may include one or more motors adapted to
move arm 202 relative to operative connection 210. In a fourth example
embodiment, first track 204 may include one or more motors adapted to
rotate arm 202 relative to first track 204. In a fifth example
embodiment, first track 204 may include first motor 1200, second motor
1202, and third motor 1204, wherein first motor 1200 is adapted to move
arm 202 relative to operative connection 210, wherein second motor 1202
is adapted to move arm 202 along first track 204, and wherein third motor
1204 is adapted to rotate arm 202 relative to first track 204.

[0083]As discussed above, first track 204 may include at least a portion
of the cable management system. That portion may include, for example,
one or more of cable guard 1228, cable guides 1230 and 1232, pulleys 1234
and 1236, and/or dual pulley assembly 1238, as well as some of the extra
components known to one of skill in the art listed above.

[0084]In an example embodiment, the umbilical cable of the cable
management system passes between cable guide 1230 and pulley 1234, then
passes between cable guide 1232 and pulley 1236, then passes through
first track 204 to dual pulley assembly 1238, then under guide block 304
and around one or both of guides 306 and 308, and then to effector 208,
optionally contacting one or more of rollers 316, 318, and 320. In a
first example embodiment, tension is maintained on the umbilical cable
that passes between cable guide 1230 and pulley 1234. In a second example
embodiment, the tension is kept substantially constant. In a third
example embodiment, the tension is kept substantially constant using a
snatch-block arrangement.

[0085]First motor 1200 and first shaft 1206 may drive arm 202 to move
relative to operative connection 210. This movement may be to expand arm
202 (i.e., to unstack first section 500, second section 502, third
section 504, and fourth section 506), or the movement may contract arm
202 (i.e., to stack first section 500, second section 502, third section
504, and fourth section 506). In an example embodiment, arm 202 may
expand to either one side or the other of operative connection 210,
providing additional flexibility in the use of apparatus 200.

[0086]As discussed above, second track 300 may include three or more
sections. For example, second track 300 may include three, four, five,
six, seven, eight, or more sections. The number of sections may be odd or
even. The number of sections that can be used is essentially a function
of the strength of the materials used to construct second track 300,
first rail 1212, and second rail 1214 (first rail 1212 and second rail
1214 support substantially the entire load of expanded second track 300
to effectively prevent this load from impacting the performance of first
shaft 1206, second shaft 1208, and/or third shaft 1210 and, hence, the
performance of first motor 1200, second motor 1202, and/or third motor
1204).

[0087]Second motor 1202 and second shaft 1208 may drive arm 202 to move
along first track 204. This "vertical" movement may be guided by first
rail 1212 and/or second rail 1214.

[0088]Third motor 1204 and third shaft 1210 may drive arm 202 to rotate
relative to first track 204. The drive train also may include, for
example, gear 1240. The rotation may be in either a clockwise or
counterclockwise sense. Thus, arm 202 may be driven in rotation to any
angular position relative to first track 204. As discussed above, when
inserting apparatus 200 into the reactor (and also when removing
apparatus 200 from the reactor), arm 202 may be rotated to be
substantially parallel to first track 204.

[0089]Arm 202 may be driven individually by first motor 1200/first shaft
1206, second motor 1202/second shaft 1208, or third motor 1204/third
shaft 1210. In addition or in the alternative, arm 202 may be
simultaneously driven by any combination of first motor 1200/first shaft
1206, second motor 1202/second shaft 1208, and/or third motor 1204/third
shaft 1210.

[0090]FIG. 15 is a perspective view of fixing device 206 of apparatus 200
of FIG. 2, while FIG. 16 is a reverse perspective view of fixing device
206 of FIG. 15. As shown in FIGS. 15 and 16, fixing device 206 may
include base 1500, plurality of legs 1502, and/or one or more pneumatic
or hydraulic pistons 1504. Advantageously, the fixing device 206 of FIGS.
15 and 16 may expand from a single driven point. The one or more
pneumatic or hydraulic piston 1504 may be positioned, oriented, and/or
connected to base 1500 and/or plurality of legs 1502 in a variety of
configurations, as is known to one of ordinary skill in the art.

[0091]In a first example embodiment, fixing device 206 may be a scissor
jack. In a second example embodiment, fixing device 206 may include one
or more scissor jacks. In a third example embodiment, fixing device 206
may include one or more hydraulic cylinders and/or one or more pneumatic
cylinders. In a fourth example embodiment, fixing device 206 may include
one or more hydraulic pistons and/or one or more pneumatic pistons.
Typically, hydraulic systems in a reactor are water-based, and hydraulic
and pneumatic systems must meet strict cleanliness and purity controls.

[0092]In another first example embodiment, a method of inspecting a
nuclear reactor may include: operatively connecting a fixing device, a
first track, an arm, and an effector to form an inspection apparatus;
inserting the inspection apparatus into the reactor; fixing the
inspection apparatus within the reactor; and operating the inspection
apparatus.

[0093]In another second example embodiment, a method of operating a
nuclear reactor may include: shutting down the nuclear reactor;
inspecting the nuclear reactor, as discussed above; and starting up the
nuclear reactor.

[0094]In another third example embodiment, a method of performing
maintenance on a nuclear reactor may include: operatively connecting a
fixing device, a first track, an arm, and one or more tools to form a
maintenance apparatus; inserting the maintenance apparatus into the
reactor; fixing the maintenance apparatus within the reactor; and
operating the maintenance apparatus.

[0095]In another fourth example embodiment, a method of operating a
nuclear reactor may include: shutting down the nuclear reactor;
performing maintenance on the nuclear reactor, as discussed above; and
starting up the nuclear reactor.

[0096]In another fifth example embodiment, a method of repairing a nuclear
reactor may include: operatively connecting a fixing device, a first
track, an arm, and one or more sensors, one or more tools, or one or more
sensors and one or more tools to form a repair apparatus; inserting the
repair apparatus into the reactor; fixing the repair apparatus within the
reactor; and operating the repair apparatus.

[0097]In another sixth example embodiment, a method of operating a nuclear
reactor may include: shutting down the nuclear reactor; repairing the
nuclear reactor, as discussed above; and starting up the nuclear reactor.

[0098]In each of these six example embodiments, the arm may have a
contracted length and an expanded length, and the expanded length may be
greater than two times the contracted length.

[0099]While example embodiments have been particularly shown and
described, it will be understood by those of ordinary skill in the art
that various changes in form and details may be made in the example
embodiments without departing from the spirit and scope of the present
invention as defined by the following claims.